Baseline urinalysis results in 32 healthy Antillean manatees (Trichechus manatus manatus)
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Aquatic Animals
Baseline urinalysis results in 32 healthy
Antillean manatees (Trichechus manatus manatus)
Lesly J. Cabrias-Contreras mvz, Dipl. OBJECTIVE
To describe results of free-catch urine samples collected from Antillean
Roberto Sánchez-Okrucky mvz manatees (Trichechus manatus manatus) under human care in the Caribbean.
Dalila Caicedo-Herrera bióloga Marina
ANIMALS
Laura Jaramillo-Ortíz mv, MSc 32 Antillean manatees in 5 Caribbean oceanaria and rescue centers.
Francisco de la Rosa dmv PROCEDURES
Ana C. Negrete-Philippe mvz Urine samples were obtained by opportunistic free catch during physi-
Danilo Cruz-Martínez mvz, phd cal examination or through the use of operant conditioning procedures.
Urinalyses consisted of macro- and microscopic evaluations, biochemical
Antonio L. Rivera-Guzmán dmv analyses with test strips, and refractometry. Results were compared for
Antonio Mignucci-Giannoni vt, phd manatees grouped on the basis of age, sex, and habitat.
From the Caribbean Manatee Conservation Center, Inter- RESULTS
American University of Puerto Rico, San Juan, Puerto Rico Urine samples were typically clear, straw colored, and alkaline (mean pH,
(Cabrias-Contreras, Rivera-Guzmán, Mignucci-Giannoni); 8.0); had a urinoid odor and low specific gravity (mean, 1.010); and had re-
Dolphin Discovery Group, Cancún, Quintana Roo, México sults on qualitative test strips that were consistently negative for the pres-
(Sánchez-Okrucky, Cruz-Martínez); Fundación Omacha,
Bogotá, Colombia (Caicedo-Herrera, Jaramillo-Ortíz); Ac- ence of glucose, bilirubin, ketones, proteins, nitrites, RBCs, and WBCs.
uario Nacional de la República Dominicana, Santo Domin- Microscopically, the mean ± SD number of RBCs and WBCs/hpf was 0.5 ±
go, República Dominicana (de la Rosa); Grupo Xcaret, Playa 0.3 RBCs/hpf and 1.1 ± 1.5 WBCs/hpf. Findings of some epithelial cells and
del Carmen, Quintana Roo, México (Negrete-Philippe); crystals were typical. Spermatozoa were found in urine from 1 of 15 sexu-
Center for Conservation Medicine and Ecosystem Health,
Ross University School of Veterinary Medicine, Basseterre, ally mature males, and parasite larvae and eggs were found in urine from 2
St. Kitts (Mignucci-Giannoni). manatees.
Address correspondence to Dr. Mignucci-Giannoni CONCLUSIONS AND CLINICAL RELEVANCE
(mignucci@manatipr.org). Results of the present study yielded the first compilation of baseline urinalysis
values in healthy Antillean manatees under human care, which, when com-
bined with physical examination and other diagnostic procedures, can help in
monitoring the health of these animals. We encourage the use of free-catch
urine collection methods, as used in the present study, for routine urinalyses
of manatees under human care in zoos, aquaria, or rescue centers. (J Am Vet
Med Assoc 2021;258:416–424)
A ntillean manatees (Trichechus manatus mana-
tus) are endangered,a euryhaline, herbivorous
aquatic mammals that live in marine, estuarine, and
free-catch urine samples collected through the use
of noninvasive medical operant conditioning in Antil-
lean manatees under human care in the Caribbean.
freshwater ecosystems of the Caribbean.1 Manatees
have been kept under human care since the 1950s,2 Materials and Methods
and although considerable attention has been given
to their care (including veterinary diagnostic proce- Animals and facilities
dures and treatments) during the past 30 years,3–7 uri- Thirty-two Antillean manatees under human
nalysis is infrequently performed in manatees housed care at 5 oceanaria and rescue center facilities in
at aquariums and zoos.8 In previous studies,8–10,b urine Colombia, Dominican Republic, Mexico, and Puerto
samples from Florida manatees (Trichechus manatus Rico were enrolled in the study, which was approved
latirostris) and Amazonian manatees (Trichechus in- by the Inter-American University Institutional Ani-
unguis) were examined. However, Antillean mana- mal Care and Use Committee and conducted in ac-
tees and Florida manatees are subspecies that differ cordance with the US Animal Welfare Act. On the
morphologically, physiologically, and genetically basis of results from physical and hematologic ex-
from each other and from Amazonian manatees,11–14 aminations, the manatees were determined to have
and there is no published information on results of been clinically normal at the time of urine sampling
urinalysis for Antillean manatees. Our aim of the between January 16, 2016, and November 20, 2019.
study reported here was to describe the macroscop- The manatees were grouped on the basis of sex, age
ic, microscopic, and biochemical characteristics of (ie, calf, juvenile, subadult, or adult15), and housing
environment (ie, freshwater, estuarine, or saltwater).
ABBREVIATIONS Water salinity at each facility was measured with a sa-
ppt Parts per thousand linity refractometer.c All facilities were located in the
SG Specific gravity tropical zone, in Caribbean waters with air tempera-
416 JAVMA | FEB 15, 2021 | VOL 258 | NO. 4Aquatic Animals
tures between 25°C and 29°C (77°F to 84.2°F) and mising the cleanliness of the genital area, which had
water temperatures between 26°C and 29°C (78.8°F been cleaned with isopropyl alcohol and allowed to
to 84.2°F). Diet consisted of aquatic plants and veg- air-dry before each sample collection.
etables for adult, subadult, and juvenile manatees. For Urine samples were collected in sterile, 120-mL
calves, natural or artificial milk formula with small polypropylene containersf or with a sterile 10- to 20-
inclusions of vegetables was fed, and depending on mL plastic syringe. Following collection, the container
each calf’s health and age, this diet was supplement- or syringe was labeled with the manatee’s name and
ed with various multivitamins and with biscuits for- the date and time of collection. Urine samples were
mulated for folivore primates.d transported to the laboratory on ice and stored, when
needed, at 4°C to 5°C (39.2°F to 41°F) until urinalysis
Sample collection was completed within 1 hour of collection.
Before a manatee’s first feeding of the day, a mid-
stream urine sample was obtained by opportunistic Urinalysis
free catch during a veterinary examination or trained Urinalysis consisted of gross examination followed
medical behaviors16–18,e (Figure 1). Urine collection by biochemical analyses and microscopic evaluation of
from manatees in Puerto Rico, Colombia, and the urine sediment as described previously.20 A standard-
Dominican Republic was strictly opportunistic dur- ized format for marine mammalsg was used to record
ing veterinary evaluations in an empty tank devoid of data, which were then transferred to a spreadsheeth
water or on land along the side of a pond enclosure. at the end of each sampling and analysis day. Prior to
Manatees were subject to regular physical examina- analysis of results, a comparison was made between
tions on the bottom of the empty tank or on land, the recorded information on the urinalysis form versus
during which the animal would typically lie in dorsal the computerized spreadsheet to identify and correct
recumbency, facilitating urine collection. In Mexi- any transcription errors, if present.
co, manatees were trained to urinate on command
through operant conditioning, similar to condition- Gross examination—A sterile, polymethylpentene
ing used in dolphins,19 except that instead of a hand plastic 50-mL graduated cylinder i was used to mea-
signal for the urination command, light hand pres- sure the volume of each urine sample. Physical char-
sure was applied in a sustained manner over the area acteristics of each sample were described, including
of the urinary bladder, just cranial to the anus. This color (ie, colorless, pale yellow, yellow, dark yellow,
pressure would trigger sufficient urination. Because dark brown-yellow, pale green-yellow, green-yellow,
sampling took several minutes in some instances, the dark green-yellow, straw, ochre, red-brown, or red),
trained behavior for urine sample collection included appearance (ie, clear, hazy, or slightly cloudy), and
allowing the manatee to breathe without compro- odor (ie none, urinoid [strong urine smell], fruity or
Figure 1—Representative photograph of the use of operant conditioning in collecting urine from 1 of the 12 Antillean manatees
(Trichechus manatus manatus) under human care in Mexico between January 19 and July 20, 2017. The manatee in the image is an
adult female.
JAVMA | FEB 15, 2021 | VOL 258 | NO. 4 417Aquatic Animals
sweet, fruity fishy [mix of sweet and fish smell], fishy, > 0 to ≤ 2.5 elements/hpf), few (mean, > 2.5 to < 5.0
grassy [smell of grass], pungent [having a sharply elements/hpf), some (mean, ≥ 5.0 to < 7.5 elements/
strong odor], sulfuric [rotten egg smell], aromatic hpf), or many (mean, ≥ 7.5 elements/hpf). Qualitative
[fragrant smell], fecal [smelling of feces], or ammonia- results for mucus were defined as none (not observed),
cal [long-standing ammonia smell]). Because physical rare (occasionally present), few (mildly present), some
characteristics of urine are subjective, the evaluators (moderately present), or many (abundantly present).
were trained in a veterinary laboratory and practiced
gross urine examination on urine collection from do- Statistical analysis
mestic mammals and dolphins. Descriptive statistics were calculated and analyzed
with statistical software.p Qualitative results were re-
Biochemical examination—Following gross exami- ported as numbers and percentages, and quantitative
nation, each urine sample was transferred to a sterile, results were reported as range and mean ± SD.21–24 Re-
15-mL conical polypropylene centrifuge tubej for bio- sults were assessed for normality of distribution with
chemical analyses with 3 different types of test strips. the Shapiro-Wilk test, and paired 2-tailed t tests were
One type of test stripk was used to assess urine SG, pH, used to evaluate for differences in mean results for
and concentrations of glucose, bilirubin, urobilinogen, manatees grouped on the basis of age, sex, and habitat.
ketones, nitrite, protein, RBCs, and WBCs. A second Values of P ≤ 0.05 were considered significant.
type of test stripl was also used to assess urine pH, and
a third type of test stripm was used to assess urine con- Results
centrations of creatinine and microalbumin. Each test
strip was immersed in the urine sample, then removed Animals
immediately. Excess urine was removed from the strip There were 32 manatees (21 males [15 sexually
by touching a paper towel to the edge of the strip. The mature] and 11 females [8 sexually mature]) under
color change for each urinalysis parameter was com- human care at 5 oceanaria and rescue center facilities
pared with a colorimetric scale supplied with the re- in Colombia (n = 9), Dominican Republic (2), Mexico
spective test strip kit, and the results were recorded. (12), and Puerto Rico (9). Of the 32 manatees, 6 were
Qualitative results for whether analytes were present calves (age, ≤ 1 year), 3 were juveniles (age, 2 to 4
versus absent (negative) were recorded, and if pres- years), 3 were subadults (age, 5 to 9 years), and 20
ent, semiquantification of results to the extent feasible were adults (age, ≥ 10). Of the 32 manatees, 13 were
with the test strips was recorded (eg, urine glucose in open marine systems (salinity range, 31 to 35 ppt),
concentration: negative vs 100, 250, 500, 1,000, or > 6 were in open cenote estuarine systems (salinity
2,000 mg/dL). Detection of semiquantitative trace con- range, 17 to 22 ppt), and 13 were in freshwater ce-
centration urobilinogen (ie, ≤ 0.2 mg/dL) was consid- ment tanks or river systems (salinity, 0 ppt).
ered a negative result for the detection of an abnormal
concentration of urobilinogen. Because a study19 of Urine samples
dolphins shows that measurements of urine SG were Free-catch urine samples were obtained by op-
inaccurate when determined with the same type of portunistic free catch during veterinary examina-
test stripk used in the present study, we also measured tions for 20 manatees and through operant condition-
urine SG using a veterinary clinical refractometern that ing procedures for 12 manatees. For the manatees
was calibrated with distilled water. with which operant conditioning was used, urination
occurred within 5 to 8 minutes after the start of the
Microscopic examination—To extract urinary sedi- requesting procedure. Overall, the mean ± SD urine
ment from each sample, approximately 3 mL of urine sample volume was 5.4 ± 1.53 mL (range, 3 to 9 mL),
was retained in the conical tube and centrifugedo for and the mean ± SD duration from collection to urinal-
2.5 minutes at 1,163 X g. Pipette aspiration was used to ysis was 19.5 ± 6.8 minutes (range, 8 to 35 minutes).
discard most of the supernatant, leaving a volume of
approximately 0.5 to 1 mL of supernatant in which the Gross examination—The color of most urine sam-
sediment pellet was resuspended. A drop of the resus- ples was straw (22/32 [69%]), followed by pale yel-
pended sediment was placed on a glass slide, covered low (6/32 [19%]) or colorless (4/32 [13%]; Table 1).
In addition, the appearance of most samples was clear
with a cover slip, and examined with light microscopy
(21/32 [66%]), and the most common odor of samples
at an absolute magnification of 100X and 400X (hpf)
was urinoid (strong urine smell; 25/32 [78%]).
to assess for WBCs, RBCs, epithelial cells (transitional,
squamous, or tubular), casts (hyaline, granular, waxy, Biochemical examination—Qualitative results of
epithelial, or fatty), crystals (calcium oxalate, uric acid, urinalyses were predominantly negative for biochem-
triple phosphate, calcium phosphate, amorphous phos- ical analytes assessed with test strips; however, semi-
phate, or urate), bacteria, yeast or fungi, spermatozoa, quantitative trace concentrations were detected for
and parasites or parasite eggs. For each urine sample, urobilinogen (0.2 mg/dL; n = 32/32), creatinine (0.1
the mean numbers of microscopy elements of interest mg/dL; 17/17), and microalbumin (10 mg/dL; 17/17;
(eg, WBCs, RBCs, and epithelial cells)/10 hpfs (400X) Table 2). The microalbumin-to-creatinine ratio was
were determined, recorded, and then qualitatively cat- 100 mg/g for all 17 manatees from which urine sam-
egorized as none (mean, 0 elements/hpf), rare (mean, ples were evaluated for both analytes.
418 JAVMA | FEB 15, 2021 | VOL 258 | NO. 4Aquatic Animals
Overall, the mean ± SD SG measured by refractom- of manatee habitat, the mean ± SD urine SG was 1.012 ±
etry was 1.010 ± 0.007 and did not differ substantially 0.009 for those in marine habitats (n = 13), 1.011 ± 0.005
between males (1.011 ± 0.008) and females (1.009 ± for those in estuarine habitats (6), and 1.008 ± 0.006 for
0.005). When considered by manatee age group, the those in freshwater habitats (13). The small number of
mean ± SD urine SG was 1.009 ± 0.004 for calves (n = manatees in each of the various categories precluded
6), 1.010 ± 0.011 for juveniles (3), 1.005 ± 0.001 for sub- further statistical analyses regarding urine SG.
adults (3), and 1.011 ± 0.008 for adults (20). On the basis Overall, the mean ± SD urine pH was 8.0 ± 0.9
and did not differ substantially between males (7.9 ±
Table 1—Gross characteristics of free-catch urine samples 1.1) and females (8.0 ± 0.7). By age group, the mean
obtained from 32 Antillean manatees (Trichechus manatus ma- ± SD urine pH was 7.8 ± 0.7 for calves, 6.7 ± 1.5 for
natus) under human care in 5 Caribbean oceanaria and rescue juveniles, 8.0 ± 0.0 for subadults, and 8.2 ± 0.9 for
centers between January 16, 2016, and November 20, 2019. adults. On the basis of manatee habitat, the mean ±
Characteristic No. (%) of urine samples SD urine pH was 8.3 ± 0.9, 8.0 ± 0.8, or 7.6 ± 1.0 for
Color
those in marine, estuarine, or freshwater habitats, re-
Straw 22 (69) spectively. Similar to findings for SG, the small num-
Pale yellow 6 (19) ber of manatees in each category precluded further
Colorless 4 (13) statistical analyses regarding urine pH.
Yellow 0
Dark yellow 0 Microscopic examination—In urinary sediments of the
Dark brown-yellow 0 32 manatees, the mean ± SD number of RBCs/hpf was 0.5
Pale green-yellow 0
Green-yellow 0 ± 0.3 (range, 0 to 3 RBCs/hpf), and the mean number of
Dark green-yellow 0 WBCs/hpf was 1.1 ± 1.5 (range, 0 to 8 WBCs/hpf), re-
Ochre 0 spectively. Qualitatively, epithelial cells were observed
Red-brown 0 in urinary samples from 28 manatees, with transitional
Red 0
cells less commonly present (1/32 [3%]), compared with
Appearance squamous cells (21/32 [66%]), which were more com-
Clear 21 (66) monly identified in samples from females (11/11 [100%])
Slightly cloudy 9 (28) versus males (10/21 [48%]; Table 3). Urinary crystals
Hazy 2 (6)
were observed in samples from 13 manatees, with cal-
Odor cium oxalate monohydrate crystals most commonly iden-
Urinoid 25 (78) tified among the affected samples (n = 4). There were
Grassy 4 (13) rare observations of mucus, erythrocyte casts, hyphae,
Fruity sweet 2 (6)
Sulfuric 1 (3) sperm, or parasite larvae and eggs, and these were found
None 0 only in samples from adult male manatees. For instance,
Fruity fishy 0 casts were present in urine samples from only 2 male
Fishy 0 manatees housed in an estuarine system in Mexico, and
Pungent 0
Aromatic 0 both manatees had RBC-type casts. In addition, these 2
Fecal 0 males had unidentified nematode-type larvae and eggs
Ammoniacal 0 observed in their urine. A summary of key urinalysis find-
Table 2—Summary urinalysis results obtained with urine test strips and refractometry used to
evaluate the urine samples from the 32 Antillean manatees described in Table 1.
No. of samples
Parameter Tested Negative Positive Range Mean ± SD
Glucose (mg/dL)* 32 32 0 — —
Bilirubin (mg/dL)* 32 32 0 — —
Urobilinogen (mg/dL)* 32 32 0 0.2† 0.2 ± 0†
Ketone (mg/dL)* 32 32 0 — —
Nitrite (mg/dL)* 32 32 0 — —
Protein (mg/dL)* 32 32 0 — —
RBCs (cells/µL)* 32 32 0 — —
WBCs (cells/µL)* 32 32 0 — —
SG‡ 32 — — 1.002–1.030 1.010 ± 0.007
pH§ 32 — — 5.0–9.5 8.0 ± 0.9
Microalbumin (mg/L)║ 17 0 17 10 10.0 ± 0
Creatinine (g/L)║ 17 0 17 0.1 0.1 ± 0
Microalbumin-to-creatinine ratio (mg/g) 17 — — 100 100 ± 0
*Measured with urine test strips.k †The finding was considered a negative result for the detection of ab-
normal urobilinogen concentration in urine. ‡Measured by refractometry. §Measured with urine test strips.l
║Measured with urine test strips.m
— = Not applicable.
JAVMA | FEB 15, 2021 | VOL 258 | NO. 4 419Aquatic Animals
Table 3—Qualitative findings from microscopic examination of the sediments in urine samples
from the 32 manatees described in Table 1.
No. (%) of samples per qualitative category*
Sediment elements No. of
of interest samples None Rare Few Some Many
Epithelial cells 32 4 (13) 6 (19) 9 (28) 12 (38) 1 (3.1)
Casts 32 30 (94) 2 (6) 0 0 0
Crystals 32 19 (60) 4 (13) 0 9 (28) 0
Bacteria 32 12 (38) 3 (10) 13 (41) 2 (6) 2 (6)
Yeast or fungi 32 30 (94) 0 2 (6) 0 0
Spermatozoa 15 14 (93) 1 (7) 0 0 0
Mucus 32 31 (97) 1 (3) 0 0 0
Parasite or ova 32 30 (94) 2 (6) 0 0 0
*For each urine sample, the mean numbers of each of the urine sediment elements of interest (eg, WBCs,
RBCs, and epithelial cells)/10 hpf [400X]) were determined, recorded, and then qualitatively categorized as none
(mean, 0 elements/hpf), rare (mean, > 0 to ≤ 2.5 elements/hpf), few (mean, > 2.5 to < 5.0 elements/hpf), some
(mean, ≥ 5.0 to < 7.5 elements/hpf), or many (mean, ≥ 7.5 elements/hpf).
Table 4—Summary of key urinalysis parameters with baseline samples from the manatees in the present study. Togeth-er
results considered clinically normal in the 32 Antillean mana- with physical examinations, hematologic and serum
tees described in Table 1. biochemical analyses, and coprologic tests, urinalysis is a
Parameter Baseline result key diagnostic tool for evaluating patients, including rou-
Gross examination tinely evaluating wild animals maintained under human
Color Straw to colorless care.26 Many zoos and aquaria have increasingly relied on
Appearance Clear training animal behaviors conducive to medical proce-
Odor Urinoid to grassy dures through operant conditioning. Because cystocen-
SG 1.003–1.017
pH 7.1–8.9 tesis or urinary catheterization would require patient re-
Urine test strip assessments straint and could result in patient resistance, injury to the
Glucose (mg/dL) Negative staff and patient, and less cooperation from the patient
Bilirubin (mg/dL) Negative in future events, the use of operant conditioning to ob-
Urobilinogen (mg/dL) ≤ 0.2
Ketone (mg/dL) Negative
tain diagnostic samples is less invasive, minimizes stress
Nitrite (mg/dL) Negative during sampling, and increases the ease in which basic
Protein (mg/dL) Negative diagnostic procedures can be performed,18 including in
RBCs (cells/µL) Negative manatees.16,17 If renal disfunction is suspected on the ba-sis
WBCs (cells/µL) Negative of results from samples collected with operant condi-
Microalbumin (mg/L) ≤ 10
Creatinine (g/L) ≤ 0.1 tioning, further tests (eg, assessments of electrolytes and
Microalbumin-to-creatinine ratio (mg/g) 100 urea waste product in urine12 and symmetric dimethylar-
ginine in bloodq) may follow to thoroughly evaluate an
Microscopy of urine sediment animal’s renal condition.
WBCs (cells/hpf [400X]) 0–2
RBCs (cells/hpf [400X]) 0–1
Results of the present study indicated that straw-
Epithelial cells* None to some colored urine was most common and considered clini-
Casts* None cally normal for the Antillean manatees in the present
Crystals* None to some study. The color is attributed to the presence of uro-
Bacteria* None to few chromes, uroerythrin, and urobilin that are formed
Yeast or fungi* None
Spermatozoa* None through bilirubin metabolism and eliminated in the
Mucus† None urine.27 This urine color was consistent with that re-
Parasites or ova of parasites* None ported in other herbivorous species, such as cattle,
goats, sheep, rabbits, rhinoceros (Rhinoceros unicor-
*Reported as the qualitative categories described in Table 3. †Qualitative
results for mucus were defined as none (not observed), rare (occasionally pres-
nis, Dicerorhinus sumatrensis, and Diceros bicornis),
ent), few (mildly present), some (moderately present), many (abundantly present). and Floridian and Amazonian manatees8,26,28,29,b but dif-
fered from the ochre or white colors of urine produced
by horses and attributed to the presence of mucus and
ings for gross, biochemical, and microscopic characteris- abundant amounts of squamosal epithelial cells.30 The
tics identified in the 32 healthy Antillean manatees under straw-colored urine of manatees in the present report
human care was compiled (Table 4). also differed from the typical yellow to dark-yellow
urine of carnivores (including dogs, cats, dolphins, and
Discussion pinnipeds), reflecting highly concentrated urine and
Urinalysis is a basic veterinary diagnostic tool used high-protein diets.19,29,30 In the present study, the small
to evaluate renal function.25 It is easy, quick, and inexpen- proportion (4/32 [13%]) of manatees with urine that
sive, and we used noninvasive techniques to obtain urine was colorless and had no alteration of other urinary pa-
420 JAVMA | FEB 15, 2021 | VOL 258 | NO. 4Aquatic Animals
rameters was similar to findings i n A mazonian m ana- Marine mammals, such as common bottlenose
tees in which dilute urine is thought to be associated dolphins, gray seals (Halichoerus grypus), and South
with intake of large quantities of water.8,31 The urine of American sea lions (Otaria byronia), tend to have
Antillean manatees sampled in the present study was acidic urine,8,19 and a previous study5 shows that Florida
predominantly clear, similar to urine from most domes- manatees also have acidic urine. However, our findings
tic and wild mammals19,29,32,33 but unlike turbid urine indicated that Antillean manatees have alkaline urine,
of horses (owing to the presence of calcium carbonate and we hypothesized that this is a consequence of her-
crystals and mucus30) and Amazonian manatees (owing bivory. Similarly, urine pH is neutral to alkaline (pH, 7.0
to the presence of cells, crystals, and bacteria29,34). to 9.0) in other herbivorous mammals (eg, cattle, sheep,
Urine odor varies among animals,26 and a urinoid goats, horses, rabbits, rhinoceros, and elephants28,29,40),
odor was most common in the urine of the Antillean likely owing to ingestion of large amounts of calcium
manatees in the present study, consistent with findings carbonate, which is eliminated by renal excretion.25
for most mammals owing to the presence of volatile Our finding that the mean ± SD urine SG was
acids and decomposition products of urea.27 Some 1.010 ± 0.007 (range, 1.002 to 1.030) was consistent
manatees in the present study had urine with a grassy with reports41,42 that manatees have poorly concen-
odor that was directly related to their herbivorous diet, trated urine under normal conditions as part of their
and a few manatees from the Dominican Republic and physiologic osmoregulation process through semire-
Puerto Rico had urine that smelled fruity sweet, which niculated kidneys. Our findings suggested that the
we presumptively related to their dietary supplementa- capacity to concentrate urine is similar between An-
tion with fruits and vitamins. Although a fruity-sweet tillean manatees and Amazonian manatees (urine SG,
odor in urine could suggest glucosuria, none of the 1.000 to 1.015),8 Florida manatees (urine SG, 1.007
manatees sampled had glucose detected in their urine. to 1.008),12,43,b various domestic species, and her-
Manatees under human care are fed diets rich in fats bivorous great apes44,45; however, domestic and wild
and carbohydrates,35 and some animals have high se- carnivores, cetaceans, and artiodactyls typically have
rum fructosamine concentrations and possible hyper- more concentrated urine.19,29,37,46
glycemia with type 2 diabetes.r In addition, previous Urinary creatinine concentrations in the Antil-
studies10,b indicate that urine glucose concentrations of lean manatees of the present study were similar to
3.9 to 6.9 mg/dL and 3.0 to 3.6 mg/dL in Floridian and those found in Amazonian and Florida manatees10,b;
Amazonian manatees, respectively, possibly reflect cattle, sheep, and goats47,48 ; domestic dogs49; com-
the intake of carbohydrate-rich foods, such as beets.30 mon bottlenose dolphins19; and harbor seals.50 In addi-
Clinicians should pay close attention to urine glucose tion, our findings for urinary microalbumin were also
concentration in manatees. within reference limits for domestic mammals.37,49
Urinalysis results with test strips were negative Further, our findings for the mean microalbumin-to-
for the detection of glucose, bilirubin, urobilinogen, creatinine ratio (100 mg/g) as an evaluation for early
ketones, nitrite, protein, blood, and leukocytes in detection of renal dysfunction30,36,51 were similar to
the Antillean manatees of the present report. These results in healthy dogs, cats, and other farm mam-
findings were consistent with those in domestic ani- mals,20,37,49,52,53 which suggested that the concentra-
mals,29,30 Asian elephants (Elephas maximus),s rhi- tions we observed were the result of physiologic ex-
noceros,28 common bottlenose dolphins (Tursiops cretion and clinically normal.
truncatus),19 and Amazonian manatees.8,10 Similarly, Epithelial cells were commonly observed in
the Antillean manatees in the present study did not urinary samples from the Antillean manatees in the
have substantial numbers of RBCs or WBCs in their present study. This finding is clinically normal in mid-
urine sediment when examined microscopically, as is stream free-catch urine samples, including in Ama-
typical of most domestic animals.36 A previous study8 zonian manatees,8 and occurs physiologically as a
involving multiple urines samples from 21 Amazoni- result of cell turnover.34 Additionally, the finding of
an manatees with reactive urinalysis strips indicated higher numbers of squamous epithelial cells in urine
most urine samples had 10 RBCs/mL and < 25 WBCs/ samples from females (vs males) may have been at-
mL; however, the investigators did not speculate on tributable to estrus cycles and associated accelerated
underlying causes, which could have in-cluded estrus detachment of vaginal epithelial cells that allowed a
in females or a urinary tract inflamma-tion.37 In the large number of these cells to be seen in the sedi-
present study, microscopic evaluation of urine ment of free-catch samples.8,54 The small numbers of
sediment revealed that the manatees had 0 to 8 transitional epithelial cells observed seemed to lack
WBCs/hpf and 0 to 3 RBCs/hpf, which were find- diagnostic importance, given that there were no as-
ings considered clinically normal because the cells sociated abnormalities in other urine parameters.38
are physiologically eliminated by the presentation Similarly, rare identification of RBC casts (only in 2
of mild inflammation, heat, and epithelial desquama- adult males) was considered a normal physiologic
tion.38,39 In contrast, Amazonian manatees have been finding similar to that in domestic animals.34,37 In
reported8 to have various numbers of WBCs and addition, our findings for urinary crystals were con-
RBCs and even suppurative exudate in their urine, sistent with those in herbivores with alkaline urine
suggesting the presence of genitourinary infections. (eg, horses,29 Asian elephants,40 rhinoceros,28 and
JAVMA | FEB 15, 2021 | VOL 258 | NO. 4 421Aquatic Animals
Amazonian and Florida manatees8,55) and other ma- Acknowledgments
rine mammals (eg, common bottlenose dolphins,56
No third-party funding or support was received in connection
ringed seals [Pusa hispida], northern elephant seals with the present study or the writing or publication of the manu-
[Mirounga angustirostris], Weddell seals [Leptony- script. The authors declare that there was no conflict of interest.
chotes weddellii], and humpback whales [Megaptera The authors thank A. M. Aguirre, T. Alejandro, L. Alvarado, M.
novaeangliae] 8,37). The small amounts of bacteria R. Arreola, L. Bustamante, L. Garduño, N. Gutiérrez, N. Jiménez, A.
and fungi or yeast observed in urine samples of the Mingramm, F. Molina, Y. Moná, C. I. Rivera, S. Rivera, A. I. Rodríguez,
and C. Rodríguez for assistance with animal training, handling, and
present study seemed to have represented contami- urine collection; B. Rivera-Marchand for statistical analysis; and G. D.
nation from free-catch sample collection in aquatic Bossart, K. Arevalo, J. C. Carrascal, M. Dennis, J. Gaspard, G. Melendez,
environments where complete sterility is difficult to and M. Walsh for assistance with the manuscript.
obtain,37,38 particularly in male manatees owing to
their long (up to approx 45 cm) tubular sheath within Footnotes
a prepuce that can harbor water from surroundings. a. Self-Sullivan C, Mignucci-Giannoni AA. Trichechus manatus.
In domestic and wild animals, the presence of fungal Gland, Switzerland: International Union for Conservation of
hyphae without accompanying abnormalities in oth- Nature and Natural Resources [database online]. Available
er urine parameters is typically considered indicative at: www.iucnredlist.org/species/22103/93569172008. Ac-
cessed January 16, 2021.
of contamination, and such has been observed in Am- b. Manire CA, Renner MS, Reidarson TH. Urinalysis and urine
azonian manatees.10 We also identified spermatozoa chemistries in the Florida manatee, Trichechus manatus
in the urine sample from 1 adult male and considered latirostris, under differing diet and salinity (abstr), in Pro-
the finding clinically normal,30,34 as was our detection ceedings. 35th Annu Conf Int Assoc Aquatic Animal Med
of mucus in urine from a male manatee.27,36 Although 2004.
c. WL0020-ATC, Tekcoplus, Hong Kong.
we did not stain slides for urinary sediment assess- d. Mazuri Leaf-Eater Primate Diet, Land O’Lakes Inc, Arden Hills,
ment because of logistic reasons owing to remote Minn.
field circumstances in the present study, future stud- e. Melesio-Navarro KM. Técnicas para la realización de exa-
ies would benefit from staining urine sediment slides men física general; pruebas de laboratorio y de gabinete
en manatíes del Caribe (Trichechus manatus manatus) al-
and thereby making it easier to identify the sediment bergados en el Acuario de Veracruz A.C. mediante condi-
structures of interest. cionamiento operante. MVZ thesis, Universidad Veracruza-
Our finding of unidentified nematode-type larvae na, Veracruz, Mexico, 2014.
and eggs in the urine samples of 2 adult male Antil- f. Urine collection container, Globe Scientific Inc, Mahwah, NJ.
lean manatees in Mexico was similar to that previous- g. Mignucci-Giannoni AA, Jiménez-Zucchet AN, Cabrias-Contreras LJ.
Marine mammal urinalysis. Centro de Conservación de Manatíes,
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